By Dani Lamorte, Pittsburgh City Paper
July 21, 2026
View the article on Pittsburgh City Paper
Peeking out from the Phipps Conservatory greenhouse is a desert show-stopper: the century plant, also known as Agave americana.
You may know agave as the origin of tequila, or as a popular houseplant, but no shot glass or bedroom nook could contain a century plant. Growing six to ten feet wide and roughly six feet tall, the plant sends up a twenty- to thirty-foot flower stalk that looks like a spear of asparagus designed by Dr. Seuss (agaves and asparagus are actually related, so that makes some sense).
At Phipps, a glass panel has been removed from the Desert Room greenhouse roof just to accommodate the floral production. To make things even more dramatic, the century plant is monocarpic, meaning it only flowers once in its multi-decade life before dying. No one makes an exit like the century plant.
While we already know the end of this agave’s story, its beginning is less certain. According to Ben Dunigan, Director of Horticulture at Phipps, the agave was planted sometime before the Conservatory’s 1993 transition from city-run facility to independent nonprofit.
“The city did not keep records of plant sources. It has been there for as long as anyone knows,” Dunigan explains.
Without records, it’s hard to date the plant exactly, but its biology gives us a clue. A. americana often reproduces via “pups” — asexually produced clones which pop up next to the “parent” plant after flowering. Back in 1968, another Agave americana bloomed at Phipps and likely produced clones which would now be 58 years old, give or take a month. Phipps estimates that the currently blooming agave is 50 to 60 years old, making it the mathematically possible progeny of the 1968 bloom. But, however the 2026 agave got there, it’s been safely ensconced in a greenhouse for almost all of its life. Its environment has been carefully monitored and adjusted.
All the while, the environment just outside that greenhouse has been changing.
Ten years after the century plant popped up through the soil, a small blurb appeared on the front page of the Pittsburgh Post-Gazette, asking citizens if they were interested in something called “community gardening.” Later that same year, the city’s first community garden — seventy plots measuring 500 square feet each — was established adjacent to Homewood Cemetery. Before gardeners had even planted a seed, however, two questions came up: What would the city do about tall “weeds” in the garden beds, and what would happen if the city needed to sell the property in the future? These questions reemerge on an almost seasonal basis, though recent changes to the city’s Adopt-a-Lot program and the creation of a new “managed natural landscape” registry aim to end these uncertainties.
In addition to questions of law and property, early community gardens also faced a new environmental pressure — acid rain. Throughout the 1970s, awareness of low-pH rain, created through the intermixing of atmospheric water with pollutants like sulfur dioxide and nitrogen dioxide, was growing among Americans. By 1979, there was serious concern that acid rain would have ecological impacts, especially here in Pennsylvania, where the rain could be as much as 2,000 times more acidic than average. By the early 1980s, it was confirmed that acid rain could harm frogs and demolish fishing stocks in Pennsylvania streams.
Compounding matters, the Clean Air Act had expired in 1981, leaving air quality enforcement in limbo. Acid levels in Pennsylvania remained high throughout the mid-1980s, but would decrease significantly following the introduction of auto emissions testing in 1984 and the US-Canada Air Quality Agreement in 1991. By 1996, acid levels had dropped as much as 25%, and today, the average pH of rain in central Pennsylvania today is close to neutral.
This trend may reverse, however. Pennsylvania State Senator Wayne Langerholc Jr. is currently promoting State Bill 1298, which would eliminate auto emissions testing in the twenty-five counties which participate in the program.
Acid wasn’t the only aqueous trouble facing the region in the 1980s. In 1988, a tank containing 3.5 million gallons of oil collapsed at an Ashland Oil Company site in Jefferson Hills, Pennsylvania. While retention dikes caught 2.5 million gallons, the remaining one million gallons spilled into the nearby Monongahela River. The spill left several communities — including Carnegie, Robinson, and North Fayette — without potable water. Twenty-nine other communities were down to a trickle at most.
In the end, the oil slick was 35 miles long and responsible for the death of 11,000 fish and 2,000 waterfowl. The cleanup process would extend into 1993, at which point Ashland entered long-term monitoring. Although the oil company paid roughly $30 million in claims, fines, and legal expenses — including the largest ever fine under the Clean Water Act at the time — most of that was paid through Ashland’s insurance policies. According to company executives, the spill had little impact on the company’s bottom line. It was a small price to pay for what newspapers called “one of the worst environmental catastrophes in the region’s history.”
Though the Phipps agave would have hardly been aware of it, its own home was facing changes, too. In 1993, the City of Pittsburgh transferred ownership of the Conservatory to the Phipps Friends nonprofit. A similar process had already taken place with the Schenley Golf Course and the Pittsburgh Aviary, greatly reducing the City’s responsibility for the attractions. A Post-Gazette editorial at the time encouraged Pittsburgh Mayor Sophie Masloff to privatize the Pittsburgh Zoo next — which would happen the following year. Looking back, we can see the risks of this approach: institutions with no stable, tax-based income, forced to devote considerable effort to fundraising rather than education or civic enrichment. Perhaps that editorial inspired the Pittsburgh-based firm Penn Mulch to begin producing a shredded newspaper-based mulch product in 1994.
Three years after Phipps went private, the Pittsburgh Parks Conservancy began to work towards a private-public partnership with the City of Pittsburgh to plan the future of, and coordinate the protection of, city parks. The alliance, formally announced by Mayor Tom Murphy in 1998, was modeled on similar partnerships in Boston, New York, and Louisville. Over the past three decades, this partnership has been at the center of managing changes to city parks — including the arrival of the emerald ash borer.
Making its first Pittsburgh appearance in 2007, the borer is a small, green insect from East Asia which lays its eggs on the bark of ash trees. When the eggs hatch, the young insects bore into the wood of the tree, chewing up the trunk layer by layer. The borer has no real predators in North America, and ash trees have no real defense against the borer, making for terrible arboreal outcomes. Borers have destroyed sixteen percent of the tree canopy in Pittsburgh parks, and tens of millions of ash trees across the country.
Alana Wenk, spokesperson for the Conservancy, says that the organization’s “restoration work — including ongoing forest restoration and invasive species management in Hays Woods Park” has allowed them to protect the remaining ash trees and “identify emerging invasive species before they’ve become widespread.” More recently, the organization has helped locals identify spotted lanternfly eggs on tree trunks, and to slow the spread of the bright red bug.
Within Frick Park, one of the city’s larger green spaces, newly arrived species haven’t been the only problem. Beginning in the 1970s, city officials — as well as officials from the adjacent boroughs of Edgewood, Wilkinsburg, and Swissvale — prevaricated on how best to clean up an area of slag, sewage, and storm runoff known colloquially as “Stink Creek.” Industrial waste, century-old plumbing, and unequal tax bases kept clean-up progress stagnant until, in the late 1990s, a state court ordered the four governments to complete the project by 2001.
Where politicians had failed, artists would succeed. In 1996, a trio of artists — Bob Bingham, Tim Collins, and Reiko Goto — formed the Nine Mile Run Greenway Project at Carnegie Mellon University’s STUDIO for Creative Inquiry. Inspired by artists like Agnes Denes, who grew a wheat field in downtown Manhattan in 1982, the project encouraged residents of the area to be imaginative about what the revitalized area could look like. As clean-up efforts took shape, the Nine Mile Run Watershed Association was formed, creating a non-governmental hub for art and science related to the area.
“We’ve installed hundreds of rain barrels, over a thousand street trees, and ten large green stormwater sites,” explains Mike Hiller, executive director of UpstreamPgh, which emerged from the Association. “Through all of these projects, we manage over seven million gallons of rainwater annually in the Nine Mile Run watershed. Most importantly, we’ve engaged thousands of people and spread the mission of clean water and climate justice throughout the region.”
Closer to the agave’s home, things were getting greener, too. In 1999, landscape architect Fred Bonci won a Pittsburgh Post-Gazette competition for the best idea to improve Oakland. Bonci’s idea was to turn back time. Situated between the Carnegie Library’s main branch, the Cathedral of Learning, and the University of Pittsburgh’s Hillman Library was a parking lot which Bonci wanted to transform into a green space. The parking lot had actually been a park about a century prior, but the automobile boom of the early 1900s changed land use priorities. Bonci’s idea was popular with residents and funders, quickly drawing financing. By 2009, the parking lot was known as Schenley Plaza, and it featured green grass, food kiosks, and a tent for private events.
The first two decades of the 2000s were a good time for parks more generally, despite the emerald ash borer’s arrival. In 2017, Pittsburgh’s ParkScore — a ranking published by the Trust for Public Lands — jumped from 39 to 23, likely owing to the opening of the Frick Environmental Center the year prior. For the next nine years, the city’s score would remain in the high teens and low twenties, reflecting increased per-capita spending on parks, a growing percentage of city land used as green space, and the opening of new park amenities.
Longstanding inequities have persisted: neighborhoods predominately occupied by people of color are 50% less likely to be within half a mile of a park, compared to predominately white neighborhoods. Working-class neighborhoods are 40% less likely to be within half a mile of a park compared to middle- and upper-class neighborhoods. While parks can be recreational, they’re also part of local ecology and human health.
Wenk of the Pittsburgh Parks Conservancy explains that “Pittsburgh’s parks form an interconnected network of forests, meadows, wetlands, and waterways that help improve air and water quality, absorb and filter stormwater, reduce urban heat, provide habitat for birds, pollinators, and other wildlife, and connect people with nature in meaningful ways.”
That network is becoming increasingly important as climatic changes are seen in the region.
“We’re already seeing the effects through more frequent heavy rain events, stronger storms, hotter summers, and shifting growing conditions,” Wenk continues.
Giovanny Giraldo, Horticultural Collections Manager at Phipps, observes the same changes and points out that smart planting and planning are necessary for the future of the city.
“Several city models around the world have pioneered efforts to increase tree coverage to reduce city temperatures and improve air quality, with additional benefits such as reduced erosion, reduced water runoff after storms, and an increased sense of well-being among inhabitants,” he says.
While undertaking this work, it’s important to keep those ParkScore inequities in mind, Giraldo says: “Some areas of the city are in greater need of tree coverage than others, particularly those with high population density and without garden spaces.”
The presence or absence of parks is easily mapped, but the biggest environmental change of the past six decades, and perhaps the change which links all the others, is harder to see directly. In 1968, atmospheric carbon dioxide (CO2) levels were measured at 320 parts per million (ppm). As of 2026, atmospheric CO2 is at 420 ppm and climbing. The global average temperature is also one degree Celcius higher than it was in 1968. Scientists warn that the planet will be, in many ways, unrecognizable if the average temperature rises 2˚C above 1968 levels. As in the 1980s, the region is forced to face the reality that industrial success is failing our environment.
But not all environmental change is disastrous, as projects like the Nine Mile Run cleanup show. In some cases, the changes are being led by nonhuman creatures.
“I see nature re-developing and slowly reclaiming Pittsburgh,” Kevin Kohl, associate professor of biology at the University of Pittsburgh tells Pittsburgh City Paper. “If we look at historical photos, the slopes were clearcut, and so the nature we do see now is through the process of succession reclaiming the land. I’m fascinated by abandoned properties that nature has reclaimed.”
Pointing to data from Tree Pittsburgh, which indicates changes in the region’s tree canopy, Kohl cautions that “humans are still at work,” and we have big questions to answer about the future of this environment, who gets to live in it, and how.
“Do we foster nature’s regrowth alongside our growth as a city? Or, do we push nature to our borders and contain it in a few parks? Do we foster biodiversity across neighborhoods, or is it a privilege for some?”
Over the next five to six decades, we’ll decide together what the next Phipps agave will see when it bursts its way through the greenhouse roof.
